This is my mistake. I completely made a mess of reading Japanese. The scroll was from ishida, Horikawa's patron, not Shioda. It is not a makimono made out to Shioda at all. I'll leave my posts up here as they hopefully will have started some fruitful discussion, but I will remove the comment from the article on Guillaume's site. I have heard about a scroll being given to Shioda, but it is only hearsay still. Apologies to Ellis, but hopefully you can run with some of my other comments.